Chemical mechanical polishing composition and method of polishing silicon nitride over silicon dioxide and simultaneously inhibiting damage to silicon dioxide

ABSTRACT

An acid chemical mechanical polishing composition polishes silicon nitride over silicon dioxide and simultaneously inhibits damage to the silicon dioxide. The acid chemical mechanical polishing composition includes polyvinylpyrrolidone polymers, anionic functional colloidal silica abrasive particles and an amine carboxylic acid. The pH of the acid chemical mechanical polishing composition is 5 or less.

FIELD OF THE INVENTION

The present invention is directed to an acid chemical mechanicalpolishing composition and method of polishing silicon nitride oversilicon dioxide and simultaneously inhibiting damage to silicon dioxide.More specifically, the present invention is directed to an acid chemicalmechanical polishing composition and method of polishing silicon nitrideover silicon dioxide and simultaneously inhibiting damage to silicondioxide, wherein the acid chemical mechanical polishing compositionincludes a polyvinylpyrrolidone polymer, anionic functional colloidalsilica abrasive particles and an amine carboxylic acid and the pH of theacid chemical mechanical polishing composition is 5 or less.

BACKGROUND OF THE INVENTION

As technology for integrated circuit devices advances, traditionalmaterials such as silicon nitride, silicon dioxide and polysilicon arebeing used in various combinations to achieve and enable desiredarchitectural configurations and device performance. Conventionalpolishing slurries have been designed for “stop on silicon nitride”applications such as in shallow trench isolation (STI). More recently,the density of integrated circuits has continued to increase, leading tonew front end of the line (FEOL) structures that benefit from chemicalmechanical polishing (CMP), including replacement metal gates, contactplugs, and substrates treated by conductive metallization. In suchstructures, silicon nitrides serve as the etch stop layer, cappingmaterial, and hard mask. In addition, silicon nitride finds increasinguse as a diffusion or passivation layer, spacer material, and liner. Inall such schemes, silicon nitride is used in combination with otherdielectric films such as silicon oxide or tetraethoxysilane (TEOS).Thus, most patterned wafers now contain both silicon nitride and silicondioxide dielectric films at different densities. Further, feature sizesteps involving such integration schemes require selective CMP polishingor removal of silicon nitride films without removing the silicon dioxidedielectric material. Other methods needing silicon nitride: silicondioxide selective CMP polishing compositions are “Reverse STI processes”where trenches are etched in the dielectric silicon dioxide and filledwith a dielectric silicon nitride cap; and alternatives to conventional“Etch Back processes” where CMP polishing is used in addition to orinstead of etching. One such example of the alternative etching processis self-aligned contact (SAC) capping. In SAC capping, replacement metalgates (RMG) have been formed of an excess of metal, such as tungsten,that has been removed by CMP polishing, and then has been etched down byreactive ion etching (RIE) which forms narrow gaps in the wafer. Thegaps are then filled with silicon nitride (SiN or Si₃N₄). CMP polishingthen removes excess silicon nitride and stops on the silicon dioxidesurface. In each case, new FEOL architectures like SAC require a reverseselectivity, i.e., a high silicon nitride removal rate with a lowsilicon dioxide oxide removal rate, in CMP polishing to remove theexcess dielectric.

In SAC, complete clearing of the silicon nitride layer over existingsilicon dioxide layers is critical to avoid blocking silicon dioxideetching in successive steps. However, over polishing of the siliconnitride thins the silicon nitride SAC cap, risking an electrical short.Therefore, CMP with high selectivity CMP polishing is critical. The newFEOL architectures all result in a structure in which a predeterminedpattern of the dielectric silicon nitride is inlaid in the siliconwafer. Such CMP polishing requires removal and planarization of asilicon nitride overburden, thereby resulting in a coplanar surface withthe silicon nitride-filled trenches, plugs, or gaps. An acceptablesilicon nitride:silicon dioxide removal rate ratio is necessary toprevent damage to the underlying silicon active areas and provide anover polish margin to ensure all pattern densities are cleared of thesilicon nitride. Further, it is even more critical to leave theunderlying silicon dioxide damage (defect, especially scratches andchatter marks) free.

Accordingly, there is a need for a chemical mechanical polishingcomposition and method which selectively polishes silicon nitride oversilicon dioxide and simultaneously prevents damage to underlying silicondioxide.

SUMMARY OF THE INVENTION

The present invention is directed to an acid chemical mechanicalpolishing composition, comprising, as initial components:

water;

anionic functional colloidal silica abrasive particles;

a polyvinylpyrrolidone polymer;

an amine carboxylic acid;

-   optionally, an anionic surfactant;-   optionally, a biocide; and,-   wherein a pH of the acid chemical mechanical polishing composition    is 5 or less.

The present invention is further directed to a method for chemicalmechanical polishing of a substrate, comprising,

providing a substrate, wherein the substrate comprises silicon nitrideand silicon dioxide;

providing a chemical mechanical polishing composition comprising, asinitial components:

water;

anionic functional colloidal silica abrasive particles;

a polyvinylpyrrolidone polymer;

an amine carboxylic acid;

-   optionally, an anionic surfactant;-   optionally, a biocide; and,-   wherein a pH of the acid chemical mechanical polishing composition    is 5 or less; and,

providing a chemical mechanical polishing pad with a polishing surface;

creating dynamic contact at an interface between the polishing surfaceof the chemical mechanical polishing pad and the substrate with a downforce of 20.7 kPa; and

dispensing the chemical mechanical polishing composition onto thechemical mechanical polishing pad at or near the interface between thechemical mechanical polishing pad and the substrate;

wherein the substrate is polished; and, wherein silicon nitride isselectively removed over silicon dioxide from the substrate.

The acid chemical mechanical polishing composition and method of thepresent invention enable selective removal of silicon nitride oversilicon dioxide in advanced design devices, such as in FEOLsemiconductor processing. Simultaneously, the acid chemical mechanicalpolishing composition and method inhibit damage to the silicon dioxide.

DETAILED DESCRIPTION OF THE INVENTION

As used throughout this specification the following abbreviations havethe following meanings, unless the context indicates otherwise: °C.=degrees Centigrade; L=liters; mL=milliliters; μ=μm=microns;kPa=kilopascal; Å=angstroms; mm=millimeters; nm=nanometers; s=seconds;min=minute; rpm=revolutions per minute; mV=millivolts; lbs=pounds;kg=kilograms; Mw=weight average molecular weight; psi=pound force persquare inch; lbf=pound force; 1 kPa=0.145038 psi; wt %=percent byweight; e.g.=for example; LPCVD=low pressure chemical vapor deposition;PECVD=plasma enhanced chemical vapor deposition; RR=removal rate;pI=isoelectric point; PS=Polishing Slurry of the Invention;CS=Comparative Polishing Slurry; PVP=polyvinylpyrrolidone;PEG=polyethylene glycol; PPG=polypropylene glycol; PVA=polyvinylalcohol; PAAm=polyacrylamide; HF=hydrogen fluoride; and SiN orSi₃N₄=silicon nitride.

The term “chemical mechanical polishing” or “CMP” refers to a processwhere a substrate is polished by means of chemical and mechanical forcesalone and is distinguished from electrochemical-mechanical polishing(ECMP) where an electric bias is applied to the substrate. The term“TEOS” means the silicon oxide formed from the decomposition oftetraethyl orthosilicate (Si(OC₂H₅)₄). The term “isoelectric point”means the pH at which an organic acid does not migrate in an electricfield or electrophoretic medium. The term “composition” and “slurry” areused interchangeably through-out the specification. The terms “a” and“an” refer to both the singular and the plural. All percentages are byweight, unless otherwise noted. All numerical ranges are inclusive andcombinable in any order, except where it is logical that such numericalranges are constrained to add up to 100%.

The chemical mechanical polishing composition and method of the presentinvention is useful for polishing a substrate comprising silicon nitride(SiN or Si₃N₄) and silicon dioxide (TEOS) and, wherein silicon nitrideremoval rate is selective over silicon dioxide removal rate. Inaddition, the chemical mechanical polishing composition and method ofthe present invention inhibits silicon wafer defects such as scratchmarks (long line of damage caused to surface), chatter marks (abrasiveroll over damage) and divots (single shallow damage). The chemicalmechanical polishing composition used in the method of the presentinvention contains (preferably consists of) water; anionic functionalcolloidal silica abrasive particles; one or more nonionicpolyvinylpyrrolidone polymers, one or more amine carboxylic acids;optionally an anionic surfactant; optionally a biocide; and wherein thechemical mechanical polishing composition has a pH of 5 or less.Preferably, the pH of the chemical mechanical polishing composition ofthe present invention is from 2 to 5, more preferably, from 3 to 5, mostpreferably, from 3 to 4.

The nonionic polyvinylpyrrolidone polymers have weight average molecularweights of 1000 or greater (e.g. 1000 to 1,000,000). Preferably, thenonionic polyvinylpyrrolidone polymers have weight average molecularweights of 1000 to 500,000 (e.g. 1000 to 450,000 or 1000 to 350,000 or10000 to 50,000), more preferably, the polyvinylpyrrolidone polymers ofthe present invention have weight average molecular weights of 3500 to360,000 (e.g. 3500 to 250,000 or 3500 to 150,000), even more preferably,the nonionic polyvinylpyrrolidone polymers of the present invention haveweight average molecular weights of 3500 to 100,000 (e.g. 3500 to 80,000or 3500 to 60,000), and most preferably, the polyvinylpyrrolidonepolymers have weight average molecular weights of 3500 to 50,000 (e.g.3500 to 20,000 or 3500 to 10,000). Polyvinylpyrrolidones of the presentinvention have a general formula:

wherein “n” is an integer greater than 1, preferably, n is an integer of10 to 50 or such as from 10 to 32.

The one or more nonionic polyvinylpyrrolidione polymers can be includedin the chemical mechanical polishing compositions of the presentinvention, as initial components, in amounts of 0.001 wt % or greater(e.g. 0.001 wt % to 1 wt % or 0.001 wt % to 0.5 wt %). Preferably, theone or more polyvinylpyrrolidone polymers are included in the chemicalmechanical polishing compositions in amounts of 0.005 wt % to 0.25 wt %(e.g. 0.005 wt % to 0.15 wt % or 0.005 wt % to 0.1 wt %), morepreferably, the one or more polyvinylpyrrolidone polymers are includedin amounts of 0.01 wt % to 0.1 wt % (e.g. 0.01 wt % to 0.08 wt % or 0.01wt % to 0.06 wt %), most preferably, the nonionic polyvinylpyrrolidonepolymers are included in the chemical mechanical polishing compositionsin amounts of 0.05 wt % to 0.1 wt % (e.g. 0.05 wt % to 0.08 wt % or 0.05wt % to 0.07 wt %).

The water contained in the chemical mechanical polishing compositionused in the chemical mechanical polishing method of the presentinvention is, preferably, at least one of deionized and distilled tolimit incidental impurities.

In accordance with the chemical mechanical polishing compositions of thepresent invention, anionic functional colloidal silica abrasive particlecompositions include, but are not limited to, a dispersion of colloidalsilica particles made by conventional sol gel polymerization or by thesuspension polymerization of water glass to produce a plurality ofelongated, bent or nodular silica particles in a distribution or mixturethat can include a plurality of spherical silica particles.

Dispersions of elongated, bent or nodular anionic functional colloidalsilica particles can be made from suspension polymerization byhydrolytic condensation of silanols formed in a known manner fromprecursors like tetraethoxysilane (TEOS) or tetramethoxysilane (TMOS).Processes for making the elongated, bent or nodular colloidal silicaparticles are known and can be found, for example, in U.S. Pat. No.8,529,787 to Higuchi et al. The hydrolytic condensation includesreacting the precursors in aqueous suspension in the presence of a basiccatalyst, such as alkylammonium hydroxides, alkoxyalkyl amines, such asethoxypropylamine (EOPA), alkylamines or potassium hydroxide,preferably, tetramethylammonium hydroxide. The elongated, bent ornodular silica particles are anionic at a pH of 5 or below.

The anionic functional groups in the one or more dispersions ofcolloidal silica abrasive particles can be sulfonic acid, such as isdisclosed in publication WO2010134542A1. In this publication, thesulfonic acid modification of silica comprises adding to silica a silanecoupling agent having a functional group which can be chemicallyconverted into a sulfonic acid group to colloidal silica and thenconverting the functional group into a sulfonic acid group. For example,the silica coupling agent, 3-mercapto propyl trimethoxysilane, which hasa mercapto group, a sulfide group or combination thereof can beconverted to a sulfonic acid group by use of an oxidizer, such ashydrogen peroxide. Another anionic functional group on the silicasurface can be a phosphonic acid group. Preferably, the colloidal silicaabrasives in the chemical mechanical polishing compositions of thepresent invention have a zeta potential from −5 mV to −50 mV at a pH of5 or less. Such a zeta potential helps control colloidal stability andsilicon nitride to silicon oxide removal rate ratio.

Examples of commercially available bent or nodular anionic colloidalsilica particles are available from Fuso Chemical Co., Ltd., Osaka, JP(Fuso) under the tradenames PL-1-D and, PL-3-D abrasive slurries.

Preferably, the colloidal silica has an average particle size of <200nm, more preferably, 10 nm to 150 nm, most preferably, 10 nm to 50 nm.The colloidal silica abrasive particles are included in the chemicalmechanical polishing composition of the present invention, as an initialcomponent, in amounts of 0.1 wt % to 10 wt %, preferably, 0.5 wt % to 5wt %, more preferably, 0.5 wt % to 1 wt %, most preferably, 0.5 wt % to0.8 wt %.

One or more amine carboxylic acids are included in the chemicalmechanical polishing composition of the present invention. The one ormore amine carboxylic acids have a pI equal to or less than 5,preferably from 2 to 4. Examples of such amine carboxylic acids areaspartic acid (pI=2.77), glutamic acid (pI=3.22), nicotinic acid(pI=3.435) and picolinic acid (pI=3.16). Preferably, the aminecarboxylic acid is picolinic acid or nicotinic acid. Most preferably,the amine carboxylic acid is nicotinic acid.

The one or more amine carboxylic acids are included in the chemicalmechanical polishing compositions of the present invention, as initialcomponents, in amounts of 0.01 wt % or greater. Preferably, the one ormore amine carboxylic acids are included in amounts of 0.01 wt % to 1 wt%, more preferably, the one or more amine carboxylic acids are includedin the chemical mechanical polishing composition in amounts of 0.05 wt %to 0.1 wt %, most preferably, from 0.06 wt % to 0.1 wt %.

Optionally, one or more anionic surfactants can be included in thechemical mechanical polishing composition of the present invention. Suchanionic surfactants include, but are not limited to, ethoxylated anionicsurfactants having a (C₆ to C₁₆) alkyl, aryl or alkylaryl hydrophobicgroup, preferably, a (C₆ to C₁₀) alkyl, aryl or alkylaryl hydrophobicgroup, preferably, the ethoxylated anionic surfactant is an ethoxylatedanionic sulfate surfactant. Examples of preferred anionic sulfatesurfactants are ethoxylated alkyl ether sulfates, such as ammonium ethersulfates. Such anionic surfactants are included in the chemicalmechanical polishing compositions to reduce roughness of silicon wafersduring polishing. An example of a commercially available alkyl ethersulfate surfactant is CEDAPAL® FA-403 ammonium ether sulfate surfactantavailable from Stepan®.

When one or more anionic surfactants are included in the chemicalmechanical polishing composition, they are included, as initialcomponents, in amounts of 0.001 wt % or greater. Preferably, they areincluded in amounts of 0.001 wt % to 1 wt %, more preferably, from0.002wt % to 0.01 wt %, most preferably from 0.003 wt % to 0.01 wt %.

Optionally, one or more biocides can be included in the chemicalmechanical polishing compositions. Such biocides include, but are notlimited to, KORDEK™ MLX (9.5-9.9% methyl-4-isothiazolin-3-one,89.1-89.5% water and ≤1.0% related reaction product) or KATHON™ ICP IIIcontaining active ingredients of 2-methyl-4-isothiazolin-3-one and5-chloro-2-methyl-4-isothiazolin-3-one, each manufactured by The DowChemical Company, (KATHON and KORDEK are trademarks of The Dow ChemicalCompany). It is preferred that biocides are included in the chemicalmechanical polishing composition.

Biocides can be included in the chemical mechanical polishingcomposition of the present invention, as an initial component, inamounts of 0.001 wt % to 0.1 wt %, preferably, 0.001 wt % to 0.05 wt %,more preferably, 0.01 wt % to 0.05 wt %, still more preferably, 0.01 wt% to 0.025 wt %.

The chemical mechanical polishing pad used in the chemical mechanicalpolishing method of the present invention can be any suitable polishingpad known in the art. The chemical mechanical polishing pad can,optionally, be chosen from woven and non-woven polishing pads. Thechemical mechanical polishing pad can be made of any suitable polymer ofvarying density, hardness, thickness, compressibility and modulus. Thechemical mechanical polishing pad can be grooved and perforated asdesired. The chemical mechanical polishing composition used in thechemical mechanical polishing method of the present invention enablesoperation with a low nominal polishing pad pressure, for example at 3 to35 kPa. Preferably, polishing is done with a platen speed of 93revolutions per minute, a carrier speed of 87 revolutions per minute, achemical mechanical polishing composition flow rate of 200 mL/min or 250mL/min, a nominal down force of 20.7 kPa on a 200 mm or 300 mm polishingmachine; and, wherein the chemical mechanical polishing pad comprises apolyurethane polishing layer containing polymeric hollow coremicroparticles and a polyurethane impregnated non-woven subpad.

The following examples are intended to illustrate the present inventionbut are not intended to limit its scope.

EXAMPLE 1 Chemical Mechanical Polishing Compositions

The following chemical mechanical polishing compositions are polishingslurries and were prepared to include the components and amountsdisclosed in Table 1 below. Nonionic polymers containing ether (—O—),hydroxyl (—OH), or >N—C(═O)— functional groups were added to selectivesilicon nitride polishing slurries. The components were combined withthe balance being deionized water. In addition, each slurry included0.0167 wt % KORDEK™ mix (10 wt % methylisothiazolinone in water)biocide. The pH of each slurry was 3.5.

TABLE 1 PL- Ammonium 1-D ™ Nicotinic Ether Additive Abrasive¹ AcidSulfate Slurry# Additive (wt %) (wt %) (wt %) (wt %)² PS-1 PVP 0.05 0.750.075 0.0031 (Mw = 10,000) PS-2 PVP 0.05 0.75 0.075 0.0031 (Mw =360,000) PS-3 PVP 0.05 0.75 0.075 0.0031 (Mw = 3500) CS-1 — 0 0.75 0.0750.0031 CS-2 PEG (Mw = 0.05 0.75 0.075 0.0031 1000) CS-3 PPG (Mw = 0.050.75 0.075 0.0031 1000) CS-4 PVA (Mw = 0.05 0.75 0.075 0.0031 10,000)¹Anionic colloidal silica abrasive particle available from Fuso ChemicalCo., Ltd, Osaka, Japan; and ²Cedapal ® FA-403 alkyl ether sulfateanionic surfactant available from Stepan ®.

andwherein “n” is an integer greater than 1.

EXAMPLE 2 SiN vs. TEOS Polishing Selectivity and Defect InhibitionPolishing Conditions:

The following tools were used for polishing experiments:

-   AMAT Reflexion polisher-   IC1000 (1010 grove) pad-   Saesol AK45 AM02BSL8031C1 disk-   20.7 kPa (3 psi) down-force-   93/87 rpm table/carrier speeds-   100% in-situ conditioning at 7 lbf pressure-   250 mL/min slurry flow rate-   300 mm silicon dioxide (TEOS) and LPCVD silicon nitride were used    for blanket wafer studies.

Post HF CMP (SP2xp) Defect Counts: Three TEOS wafers were used as defectmonitor wafers for each slurry. Each defect wafer was polished for 60 sat 3 psi, 93/87 rpm and 250 mL/min slurry flow rate. Wafers were thenexposed to a 1.92 wt. % HF solution for a time sufficient to remove 200Å of a given substrate, using a M3307-2949 Veeco™ HF cleaner (Veeco,Horsham, Pa.). Wafers were then scanned on a Surfscan™ SP2xp metrologytool (KLA-Tencor, Milpitas, Calif.) to get Post HF defect wafer maps,followed by automatic SEM review of 100 random defects for scratches,chatter marks, and divots. Klarity defect software (KLA-Tencor,Milpitas, Calif.) was used to extract Post CMP total defect counts foreach wafer. Defect counts should be as low as possible. Average value ofthese three wafers were taken and normalized to that of base lineslurry.

Removal Rate: Removal rate (RR) was determined from amount removed inone minute polishing. Average value of the three wafers are reported inTable 2. Amount removed was determined from the change in the dielectricfilm thicknesses before and after polishing using a KLA-Tencor™ FX200metrology tool (KLA Tencor, Milpitas, Calif.) using a 65 point spiralscan with a 3 mm edge exclusion.

TABLE 2 Normalized Extrapolated Scratches + Normalized Chatter SiN RRTEOS RR SiN:TEOS Post HF Marks + Slurry# (Å/min) (Å/min) RR RatioDefect# Divot PS-1 549 4 137 0.33 0.3 PS-2 532 10 52 0.26 0.26 PS-3 5563 172 0.32 0.3 CS-1 577 7 81 1 1 CS-2 627 6 100 0.92 0.83 CS-3 800 9 901.62 2.2 CS-4 592 12 50 1.64 2.16

Nonionic polymers of polyvinylpyrrolidone showed significant defectinhibition in contrast to the comparative slurries which did not includepolyvinylpyrrolidone nonionic polymers. In addition, chemical mechanicalpolishing slurries which included nonionic polyvinylpyrrolidone polymershaving weight average molecular weights of 3500 and 10,000 showedimproved selectivity of SiN over TEOS.

EXAMPLE 3 Chemical Mechanical Polishing Compositions

The following chemical mechanical polishing compositions are polishingslurries and were prepared to include the components and amountsdisclosed in Table 3 below. Nonionic polymers containing >N—C(═O)—functional group were added to selective silicon nitride polishingslurries. The components were combined with the balance being deionizedwater. In addition, each slurry included 0.0167 wt % KORDEK™ mix (10 wt% methylisothiazolinone in water) biocide. The pH of each slurry was3.5.

TABLE 3 PL- Ammonium 1-D ™ Nicotinic Ether Additive Abrasive¹ AcidSulfate Slurry# Additive (wt %) (wt %) (wt %) (wt %)² PS-4 PVP (Mw =0.05 0.75 0.075 0.0031 10,000) CS-5 — 0 0.75 0.075 0.0031 CS-6 PAAm 0.050.75 0.075 0.0031 ¹Anionic colloidal silica abrasive particle availablefrom Fuso Chemical Co., Ltd, Osaka, Japan; and ²Cedapal ® FA-403 alkylether sulfate anionic surfactant available from Stepan ®.

andwherein “n” is an integer greater than 1.

EXAMPLE 4 SiN vs. TEOS Polishing Selectivity and Defect Inhibition

Polishing conditions, Post HF (SP2xp) defect count and removal rate forthe chemical mechanical polishing compositions in Example 3 above weredone using the apparatus and following the procedures of Example 2above.

TABLE 4 Extrapolated Scratches + SiN RR TEOS RR SiN:TEOS Post HF ChatterSlurry# (Å/min) (Å/min) RR Ratio Defect# Marks PS-4 567 3 200 0.28 0.18CS-5 623 7 88 1 1 CS-6 600 7 87 1.45 1.36Nonionic polymers containing >N—C(═O)— functionality were compared. Thechemical mechanical polishing composition containing nonionicpolyvinylpyrrolidone showed significant defect improvement over theslurry which did not include a nonionic polymer as well as the chemicalmechanical polishing slurry which contained PAAm.

EXAMPLE 5 Chemical Mechanical Polishing Compositions

The following chemical mechanical polishing compositions are polishingslurries and were prepared to include the components and amountsdisclosed in Table 5 below. Nonionic polymers containing >N—C(═O)—functional group were added to selective silicon nitride polishingslurries. The components were combined with the balance being deionizedwater. In addition, each slurry included 0.0167 wt % KORDEK™ mix (10 wt% methylisothiazolinone in water) biocide. The pH of each slurry was3.5.

TABLE 5 PL- Ammonium 1-D ™ Nicotinic Ether Additive Abrasive¹ AcidSulfate Slurry# Additive (wt %) (wt %) (wt %) (wt %)² PS-5 PVP (Mw =0.05 0.75 0.075 0.0031 10,000) PS-6 PVP (Mw = 0.1 0.75 0.075 0.003110,000) CS-7 — 0 0.75 0.075 0.0031 ¹Anionic colloidal silica abrasiveparticle available from Fuso Chemical Co., Ltd, Osaka, Japan; and²Cedapal ® FA-403 alkyl ether sulfate anionic surfactant available fromStepan ®.

EXAMPLE 6 SiN vs. TEOS Polishing Selectivity and Defect Inhibition

Polishing conditions, Post HF (SP2xp) defect count and removal rate forthe chemical mechanical polishing compositions in Example 5 above weredone using the apparatus and following the procedures of Example 2above.

TABLE 6 Extrapolated Scratches + SiN RR TEOS RR SiN:TEOS Post HF ChatterSlurry# (Å/min) (Å/min) RR Ratio Defect# Marks PS-5 567 3 200 0.28 0.18PS-6 541 2 243 0.17 0.05 CS-7 623 7 88 1 1The chemical mechanical polishing compositions containing nonionicpolyvinylpyrrolidone showed significant defect improvement over theslurry which did not include a polyvinylpyrrolidone nonionic polymer.

EXAMPLE 7 Chemical Mechanical Polishing Compositions

The following chemical mechanical polishing compositions are polishingslurries and were prepared to include the components and amountsdisclosed in Table 7 below. The components were combined with thebalance being deionized water. In addition, each slurry included 0.0167wt % KORDEK™ mix (10 wt % methylisothiazolinone in water) biocide. ThepH of each slurry was 3.5.

TABLE 7 PL- Ammonium 1-D ™ Nicotinic Ether Additive Abrasive¹ AcidSulfate Slurry# Additive (wt %) (wt %) (wt %) (wt %)² PS-7 PVP (Mw =0.05 0.75 0.075 0.0031 10,000) PS-8 PVP (Mw = 0.05 0.75 0.075 0 10,000)¹Anionic colloidal silica abrasive particle available from Fuso ChemicalCo., Ltd, Osaka, Japan; and ²Cedapal ® FA-403 alkyl ether sulfateanionic surfactant available from Stepan ®.

EXAMPLE 8 SiN vs. TEOS Polishing Selectivity, Defect Inhibition andPolysilicon Roughness

Polishing conditions, Post HF (SP2xp) defect count and removal rate forthe chemical mechanical polishing compositions in Example 7 above weredone using the apparatus and following the procedures of Example 2above. Roughness was measured using Dimension Atomic Force profiler(DAFP) (Bunker Corporation, Billerica, Mass., Model #3200). The DAFPprovided a 3-dimensional profile on a nano-scale by measuring forcesbetween a sharp probe (radius less than 10 nm) and surface at very shortdistance (0.2-10 nm probe sample separation).

TABLE 8 Polycrystalline Silicon Film SiN RR TEOS RR SiN:TEOS Post HFRoughness Slurry# (Å/min) (Å/min) RR Ratio Defect# (Å) PS-7 532 4 1290.18 5 PS-8 566 4 153 0.1 10The anionic surfactant ammonium ether sulfate did not influence SiN:TEOSpolishing performance including defect and scratch inhibition. However,the anionic surfactant helped reduce surface roughness on thepolycrystalline silicon film.

EXAMPLE 9 Chemical Mechanical Polishing Compositions

The following chemical mechanical polishing compositions are polishingslurries and were prepared to include the components and amountsdisclosed in Table 9 below. The components were combined with thebalance being deionized water. In addition, each slurry included 0.0167wt % KORDEK™ mix (10 wt % methylisothiazolinone in water) biocide. CS-8and CS-9 were adjusted to alkaline pH values with ammonium hydroxide.

TABLE 9 Ammonium PL-1-D ™ Nicotinic Ether Additive Abrasive¹ AcidSulfate Slurry# Additive (wt %) (wt %) (wt %) (wt %)² pH PS-9 PVP 0.050.75 0.075 0.0031 3.5 (Mw = 10,000) PS-10 PVP 0.05 0.75 0.075 0.0031 5(Mw = 10,000) CS-8 PVP 0.05 0.75 0.075 0.0031 8 (Mw = 10,000) CS-9 PVP0.05 0.75 0.075 0.0031 10.5 (Mw = 10,000) ¹Anionic colloidal silicaabrasive particle available from Fuso Chemical Co., Ltd Osaka, Japan;and ²Cedapa ® FA-403 alkyl ether sulfate anionic surfactant availablefrom Stepan ®.

EXAMPLE 10 The pH Effect on SiN and TEOS Removal Rate PolishingConditions:

The following tools were used for polishing experiments:

-   Strausbaugh 6EE polisher-   IC1000 (1010 grove) pad-   Saesol AK45 AM02BSL8031C1 disk-   20.7 kPa (3 psi) down-force-   93/87 rpm table/carrier speeds-   100% in-situ conditioning at 7 lbf pressure-   200 mL/min slurry flow rate-   200 mm silicon dioxide (TEOS) and PECVD silicon nitride were used    for blanket wafer studies.

Removal Rate: Removal rate (RR) was determined from amount removed inone minute polishing. Average value of the three wafers are reported inTable 10. Amount removed was determined from the change in thedielectric film thicknesses before and after polishing using aKLA-Tencor™ FX200 metrology tool (KLA Tencor, Milpitas, Calif.) using a65 point spiral scan with a 3 mm edge exclusion.

TABLE 10 SiN RR TEOS RR SiN:TEOS Slurry# pH (Å/min) (Å/min) RR RatioPS-9 3.5 860 1 860 PS-10 5 477 1 477 CS-8 8 4 2 2 CS-9 10.5 15 3 5

The SiN removal rate dropped significantly above pH 5. Accordingly,alkaline pH ranges were shown to be unsuitable for selective polishingof SiN over TEOS.

1. An acid chemical mechanical polishing composition, consisting of, asinitial components: water; anionic functional colloidal silica abrasiveparticles; a polyvinylpyrrolidone polymer; an amine carboxylic acidselected from the group consisting of nicotinic acid and picolinic acid;optionally an anionic surfactant; optionally a biocide; and, wherein apH of the acid chemical mechanical polishing composition is 5 or less.2. The chemical mechanical polishing composition of claim 1, wherein thechemical mechanical polishing composition consists of, as initialcomponents: the water; the anionic functional colloidal silica abrasiveparticles; the polyvinylpyrrolidone polymer, wherein thepolyvinylpyrrolidone polymer has a weight average molecular weight of1000 or greater; the amine carboxylic acid selected from the groupconsisting of nicotinic acid and picolinic acid; optionally, the anionicsurfactant; a biocide; and. wherein the pH of the chemical mechanicalpolishing composition is from 2-5.
 3. The chemical mechanical polishingcomposition of claim 2, wherein the chemical mechanical polishingcomposition consists of, as initial components: the water; 0.1 wt % to10 wt % of the anionic functional colloidal silica abrasive particles;0.001 wt % or greater of the polyvinylpyrrolidone polymer, wherein thepolyvinylpyrrolidone polymer has a weight average molecular weight of3000 to 500,000; the amine carboxylic acid selected from the groupconsisting of nicotinic acid, and picolinic acid, wherein the aminecarboxylic acid has an isoelectric point of less than 5; the anionicsurfactant; the biocide; and wherein the pH of the chemical mechanicalpolishing composition is from 3-5.
 4. The chemical mechanical polishingcomposition of claim 3, wherein the chemical mechanical polishingcompositions consists of as initial components: the water; 0.5 wt % to 5wt % of the anionic functional colloidal silica abrasive particles;0.005 wt % to 0.25 wt % of the polyvinylpyrrolidone polymer, wherein thepolyvinylpyrrolidone polymer has a weight average molecular weight of3500 to 360,000; 0.01 wt % or greater of the amine carboxylic acidselected from the group consisting of nicotinic acid and picolinic acid,wherein the amine carboxylic acid has an isoelectric point of less than5; 0.001 wt % or greater of the anionic surfactant; 0.001 wt % to 0.1 wt% of the biocide; and wherein the pH of the chemical mechanicalpolishing composition is from 3-4.
 5. A method for chemical mechanicalpolishing of a substrate, comprising: providing a substrate, wherein thesubstrate comprises silicon nitride and silicon dioxide; providing anacid chemical mechanical polishing composition consisting of, as initialcomponents: water; anionic functional colloidal silica abrasiveparticles; a polyvinylpyrrolidone polymer; an amine carboxylic acidselected from the group consisting of nicotinic acid and picolinic acid;optionally, an anionic surfactant; optionally, a biocide; and, wherein apH of the chemical mechanical polishing composition is 5 or less; andproviding a chemical mechanical polishing pad with a polishing surface;creating dynamic contact at an interface between the polishing surfaceof the chemical mechanical polishing pad and the substrate with a downforce of 20.7 kPa; and dispensing the chemical mechanical polishingcomposition onto the chemical mechanical polishing pad at or near theinterface between the chemical mechanical polishing pad and thesubstrate; wherein the substrate is polished; and, wherein siliconnitride is selectively removed over silicon dioxide from the substrate.6. The method of claim 5, wherein the chemical mechanical polishingcomposition provided consists of, as initial components: water; theanionic functional colloidal silica abrasive particles; thepolyvinylpyrrolidone polymer, wherein the polyvinylpyrrolidone polymerhas a weight average molecular weight of 1000 or greater; the aminecarboxylic acid selected from the group consisting of nicotinic acid andpicolinic acid; optionally, the anionic surfactant; a biocide; and.wherein the pH of the chemical mechanical polishing composition is from2-5; and providing the chemical mechanical polishing pad with thepolishing surface; creating dynamic contact at the interface between thepolishing surface of the chemical mechanical polishing pad and thesubstrate with a down force of 20.7 kPa; and dispensing the chemicalmechanical polishing composition onto the chemical mechanical polishingpad at or near the interface between the chemical mechanical polishingpad and the substrate; wherein the substrate is polished; and, whereinsilicon nitride is selectively removed over silicon dioxide from thesubstrate.
 7. The method of claim 6, wherein the chemical mechanicalpolishing composition consists of, as initial components: water; 0.1 wt% to 10 wt % of the anionic functional colloidal silica abrasiveparticles; 0.001 wt % or greater of the polyvinylpyrrolidone polymer,wherein the polyvinylpyrrolidone polymer has a weight average molecularweight of 3000 to 500,000; the amine carboxylic acid selected from thegroup consisting of nicotinic acid and picolinic acid, wherein the aminecarboxylic acid has an isoelectric point of less than 5; the anionicsurfactant; the biocide; and wherein the pH of the chemical mechanicalpolishing composition is from 3-5; and providing the chemical mechanicalpolishing pad with the polishing surface; creating dynamic contact atthe interface between the polishing surface of the chemical mechanicalpolishing pad and the substrate with a down force of 20.7 kPa; anddispensing the chemical mechanical polishing composition onto thechemical mechanical polishing pad at or near the interface between thechemical mechanical polishing pad and the substrate; wherein thesubstrate is polished; and, wherein silicon nitride is selectivelyremoved over silicon dioxide from the substrate.
 8. The method of claim7, wherein the chemical mechanical polishing composition consists of, asinitial components: water; 0.5 wt % to 5 wt % of the anionic functionalcolloidal silica abrasive particles; 0.005 wt % to 0.25 wt % of thepolyvinylpyrrolidone polymer, wherein the polyvinylpyrrolidone polymerhas a weight average molecular weight of 3500 to 360,000; 0.01 wt % orgreater of the amine carboxylic acid selected from the group consistingof nicotinic acid and picolinic acid, wherein the amine carboxylic acidhas an isoelectric point of less than 5; 0.001 wt % or greater of theanionic surfactant; 0.001 wt % to 0.1 wt % of the biocide; and whereinthe pH of the chemical mechanical polishing composition is from 3-4; andproviding the chemical mechanical polishing pad with the polishingsurface; creating dynamic contact at the interface between the polishingsurface of the chemical mechanical polishing pad and the substrate witha down force of 20.7 kPa; and dispensing the chemical mechanicalpolishing composition onto the chemical mechanical polishing pad at ornear the interface between the chemical mechanical polishing pad and thesubstrate; wherein the substrate is polished; and, wherein siliconnitride is selectively removed over silicon dioxide from the substrate.